Detoxification studies using noxious lipophilic foreign and endogenous compounds have continued with conjugation reactions with UDP glucuronosyltransferase activities which are differentially induced in mice and rat by phenobarbital-like or aromatic hydrocarbon-like compounds. Antibodies raised against a mouse purified UDP glucuronosyltransferase enzyme of 51 K dalton directly immunoprecipitates the 51 K dalton antigen and the appropriate activities and indirectly immunoprecipitates 54 K dalton transferase activities. The results suggest antibodies were raised against a common determinant (monovalent) in many transferases and that in the antigen multiple determinants were effective. The monovalent antibody population may, therefore, select for a common transmembrane sequence or a UDP glucuronic acid binding site in the transferases. The two transferases were similar according to peptide map, but according to in vitro translation followed by processing with dog pancreatic microsomes and by endoglycosidase H treatment, only the 51 K dalton protein is glycosylated to generate the mature form. Transferase specific mRNAs from mouse and rat have been immunoenriched from polysomes from rat and mouse and used as templates to make ds DNA. The ds DNA was recombined into PBR322 plasmids which were transfected into E. coli X1776. The resulting transferase clones are currently being characterized.